Thirty one common fruit extracts were screened for their antioxidant potential by using ABTS•+ and DPPH• radical scavenging assays and iron chelating capacity. Among them, the extract of Grewia asiatica L. (Phalsa) exhibited not only good in-vitro radical scavenging and iron chelating activity but also found to be good in in-vivo antioxidant and hepatoprotective activity by normalizing liver enzymes levels in animal model. Antioxidant-activity guided isolation of fruits of G. asiatica L., leads to the isolation of new compound, isorhamnetol 5-O-[6″-(3-hydroxy-3-methyl glutarate)]β-D-glucodise β-D-glucoside (1) in addition to kaempferol 3-O-β-D-glucoside (2), kaempferol 3-O-α-D-rhamnoside (3), quercetin 3-O-β-D-glucoside (4), quercetin 3-O-β-D-rhamnoside (5), quercetin 3-O-(2-p-courmaroylglucoside (6), myricetin 3-O-β-D-xyloside (7), 5-hydroxymethylfurfural (8), 3,4-dihydroxybenzoic acid (9), 1,5-dimethyl citrate (10), and trimethyl citrate (11). The structures of the isolated compounds were deduced by using mass spectrometry and 1D- and 2D-NMR techniques. Trolox equivalent antioxidant capacity (TEAC) measurements on compounds 1-11 were also carried out and potent antioxidant activity was observed.
The fruits of Grewia asiatica L., was identified as potential crop for nutraceutical products as number of bioactive compounds were identified and characterized. Further investigations are needed at molecular level to explore the mechanism of action of active ingredients.